As someone who just planted vines this year, and wanting to avoid “black rot” - how do you prevent this from happening? What causes it?
Use protective fungicide sprays. Pesticides registered to protect the developing new growth include
copper,
captan, ferbam, mancozeb, maneb, triadimefon, and ziram. Important spraying times are as new shoots are 2 to 4 inches long, and again when they are 10 to 15 inches long, just before bloom, just after bloom, and when the fruit has set.
Cultivars with large, juicy berries are the most susceptible. In general, grapes that ripen late in the season are affected the least. Most commercial cultivars are sufficiently resistant if adequately protected with a fungicide spray program. ‘Baco #1’, ‘Cascade’, ‘Cayuga White’, ‘Chancellor’, ‘Chelois’, ‘DeChaunac’, ‘Elvira’, ‘Missouri Riesling’, ‘Norton’, ‘Vidal 256’, and ‘Verdelet’ are varieties which are moderately resistant.